By all definitions, President Donald Trump is an online troll. As of Feb. 27, the 45th president has lashed out at 319 entities, just on Twitter:elected officials, news organizations, corporations, celebrities, countries, education policies and speeches.

Now,thepublic– one of the president's 319 targets –is trolling right back, leaving bad online reviews of his hotels, restaurants and resorts. Business Insider reports that the average ratings on Yelp and Google for Trump's eponymous holdings have fallen 40 percent, to about 3.7 stars, since he took office in January. Around the time of the election, the properties had an average 4-star rating.

The decline, documentedby online rating and review consulting firm Signpost, could cost the Trump brand at least $66 million in revenue over the next four years if it continues.

That's because ratings affect revenues. Harvard Business School documented in 2011 that each star added to a restaurant's Yelp review resulted in a 5 to 9 percent effect on revenue. The same goes for the reverse: Losing stars means losing revenue.

Trump's brand also faces an uphill battle in Google searches, where competitors with better ratings are given more visibility.

Signpost CEO Stuart Wall said more than 90 percent of people look at a company's rating before doing business with them.

But many of the reviews left online are politically motivated, submitted by people who have never visited the businesses. Yelp is monitoring several of Trump's businesses for content relating to current events, including Trump Grill in New York City, the Trump International Hotel Las Vegas and theMar-a-LagoClubin Palm Beach, Florida.

Some properties have been hit harder than others. The president's Las Vegas hotel holds afour-star rating, while the recently opened International Hotel in Washington, D.C. has a2.5-starrating. Mar-a-Lago, dubbed the president's Winter White House that charges a $200,000 initiation fee, has atwo-star ratingon Yelp.